The invention relates to a method for fabricating a photomask and, more particularly, to a method for correcting a pattern critical dimension (CD) in a photomask.
In a process of fabricating a semiconductor device, a photomask formed with a pattern is used to realize a pattern to be formed in a wafer. Since the pattern formed over the photomask is transferred onto the wafer, the method of fabricating the photomask is very important.
As the degree of integration degree of semiconductors has increased, the size of patterns forming the semiconductor device have become increasingly miniaturized. Accordingly, the patterns formed over the photomask have a finer CD. In the fabrication of the photomask, a light-shielding layer and a first resist layer are first formed, and an exposure process and a development process are performed on the first resist layer to form a first resist layer pattern. An exposed portion of the light-shielding layer is etched using the first resist layer pattern as an etch mask to form a light-shielding layer pattern, and the first resist layer pattern is then removed.
However, in the fabrication process of the photomask, some of the patterns can be formed relatively larger or smaller than a CD to be formed due to an insufficient etch margin, a defect of a process apparatus, and the like. As such, the mask pattern having CD difference from the target CD is transferred as it is to thereby result in a defect in wafer patterns.